$fh = FileHandle->new("file", "r"); if (defined $fh) { print <$fh>; undef $fh; # automatically closes the file }
$fh = FileHandle->new("file", O_WRONLY|O_APPEND); if (defined $fh) { print $fh "corge\n"; undef $fh; # automatically closes the file }
$pos = $fh->getpos; $fh->setpos($pos);
$fh->setvbuf($buffer_var, _IOLBF, 1024);
($readfh, $writefh) = FileHandle::pipe;
autoflush STDOUT 1;
=head1 DESCRIPTION
NOTE: This class is now a front-end to the IO::* classes.
C<FileHandle::new> creates a C<FileHandle>, which is a reference to a newly created symbol (see the C<Symbol> package). If it receives any parameters, they are passed to C<FileHandle::open>; if the open fails, the C<FileHandle> object is destroyed. Otherwise, it is returned to the caller.
C<FileHandle::new_from_fd> creates a C<FileHandle> like C<new> does. It requires two parameters, which are passed to C<FileHandle::fdopen>; if the fdopen fails, the C<FileHandle> object is destroyed. Otherwise, it is returned to the caller.
C<FileHandle::open> accepts one parameter or two. With one parameter, it is just a front end for the built-in C<open> function. With two parameters, the first parameter is a filename that may include whitespace or other special characters, and the second parameter is the open mode, optionally followed by a file permission value.
If C<FileHandle::open> receives a Perl mode string (">", "+<", etc.) or a POSIX fopen() mode string ("w", "r+", etc.), it uses the basic Perl C<open> operator.
If C<FileHandle::open> is given a numeric mode, it passes that mode and the optional permissions value to the Perl C<sysopen> operator. For convenience, C<FileHandle::import> tries to import the O_XXX constants from the Fcntl module. If dynamic loading is not available, this may fail, but the rest of FileHandle will still work.
C<FileHandle::fdopen> is like C<open> except that its first parameter is not a filename but rather a file handle name, a FileHandle object, or a file descriptor number.
If the C functions fgetpos() and fsetpos() are available, then C<FileHandle::getpos> returns an opaque value that represents the current position of the FileHandle, and C<FileHandle::setpos> uses that value to return to a previously visited position.
If the C function setvbuf() is available, then C<FileHandle::setvbuf> sets the buffering policy for the FileHandle. The calling sequence for the Perl function is the same as its C counterpart, including the macros C<_IOFBF>, C<_IOLBF>, and C<_IONBF>, except that the buffer parameter specifies a scalar variable to use as a buffer. WARNING: A variable used as a buffer by C<FileHandle::setvbuf> must not be modified in any way until the FileHandle is closed or until C<FileHandle::setvbuf> is called again, or memory corruption may result!
See L<perlfunc> for complete descriptions of each of the following supported C<FileHandle> methods, which are just front ends for the corresponding built-in functions:
close fileno getc gets eof clearerr seek tell
See L<perlvar> for complete descriptions of each of the following supported C<FileHandle> methods:
Furthermore, for doing normal I/O you might need these:
=over 4
=item $fh->print
See L<perlfunc/print>.
=item $fh->printf
See L<perlfunc/printf>.
=item $fh->getline
This works like <$fh> described in L<perlop/"I/O Operators"> except that it's more readable and can be safely called in a list context but still returns just one line.
=item $fh->getlines
This works like <$fh> when called in a list context to read all the remaining lines in a file, except that it's more readable. It will also croak() if accidentally called in a scalar context.
=back
There are many other functions available since FileHandle is descended from IO::File, IO::Seekable, and IO::Handle. Please see those respective pages for documentation on more functions.
=head1 SEE ALSO
The B<IO> extension, L<perlfunc>, L<perlop/"I/O Operators">.